The Complete Book of Spaceflight: From Apollo 1 to Zero Gravity

stage engines were ignited 6 seconds before liftoff.
The center F-1 was shut down 135 seconds after
launch and the outer four F-1s 15 seconds later. One
second following cutoff of the four outer F-1s, the
first stage separated. Simultaneously, eight retro-
rockets were fired briefly to slow the first stage and to
prevent it from bumping into the second stage. Following
separation, the spent first stage fell into the Atlantic
about 640 km downrange. One second after firststage
separation, eight solid-fueled motors mounted
Saturn V The Apollo 11 Saturn V lifts off with astronauts Neil Armstrong, Michael Collins, and Edwin Aldrin aboard. NASA
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